Conventionally, an ink jet printer which uses an ultraviolet curing type ink for printing has been widely used (for example, see Non-patent literature 1). In such an ink jet printer, normally, ink droplets are ejected from an ink jet head toward a medium and ultraviolet rays are irradiated to the dots of ink which are formed by the ink droplets having been landed on the medium to cure the ink. Further, in recent years, since demanded print resolution and print quality become higher, printing in a multi-pass method has been widely used in which a plurality of main scanning operations is performed at each position of a printing region to be printed.    [Non-patent literature 1] Internet URL http://www.mimaki.co.jp